﻿// Copyright (c) 2011 Blue Onion Software, All rights reserved
using System;
using System.Collections.Generic;
using System.IO;
using System.IO.Compression;
using System.Text;

namespace BlueOnionSoftware.Bloget
{
    internal static class SimpleZip
    {
        public static void ZipTo(IEnumerable<string> fileNames, Stream archiveStream)
        {
            ZipTo(fileNames, archiveStream, false);
        }

        public static void ZipTo(IEnumerable<string> fileNames, Stream archiveStream, bool flatten)
        {
            Throw.IfNull(fileNames, "fileNames");
            Throw.IfNull(archiveStream, "archiveStream");

            if (archiveStream.CanWrite == false)
            {
                throw new ArgumentException("archiveStream is not writable");
            }

            var compressedFiles = new List<CompressedFile>();

            using (var counterStream = new CounterStream(archiveStream, true))
            {
                foreach (var file in fileNames)
                {
                    var compressedFile = new CompressedFile(file, counterStream.Position, flatten);
                    compressedFile.EmitFileHeader(counterStream);
                    compressedFile.EmitFile(counterStream);
                    compressedFiles.Add(compressedFile);
                }

                var centralDirectoryOffset = counterStream.Position;

                foreach (var compressedFile in compressedFiles)
                {
                    compressedFile.EmitCatalogFileHeader(counterStream);
                }

                var centralDirectorySize = counterStream.Position - centralDirectoryOffset;

                Write(0x06054b50, counterStream); // End of central directory
                Write(0, counterStream); // number of this disk
                Write(0, counterStream); // disk number of central directory
                Write((ushort) compressedFiles.Count, counterStream); // total # of files on this disk
                Write((ushort) compressedFiles.Count, counterStream); // total # of files in central directory
                Write((uint) centralDirectorySize, counterStream);
                Write((uint) centralDirectoryOffset, counterStream);
                Write(0, counterStream); // Zip file comment length
                counterStream.Flush();
            }
        }

        // -------------------------------------------------------------------------------------------------

        private sealed class CompressedFile
        {
            private string FileName { get; set; }
            private int RelativeOffset { get; set; }
            private ushort GeneralPurpose { get; set; }
            private ushort StoreMethod { get; set; }
            private uint DosDateTime { get; set; }
            private uint Checksum { get; set; }
            private int CompressedLength { get; set; }
            private int UncompressedLength { get; set; }
            private string Name { get; set; }

            public CompressedFile(string fileName, long relativeOffset, bool flatten)
            {
                FileName = fileName;
                Name = NormalizeFileName(fileName, flatten);
                RelativeOffset = (int) relativeOffset;
                var fileInfo = new FileInfo(FileName);
                GeneralPurpose = 8;
                DosDateTime = GetDosDateTime(fileInfo.LastWriteTime);
                StoreMethod = (ushort) ((fileInfo.Length < 50) ? 0 : 8);
            }

            public void EmitFileHeader(Stream stream)
            {
                GeneralPurpose = stream.CanSeek ? (ushort) 0 : (ushort) 8;

                Write(0x04034b50, stream); // signature
                Write(0x14, stream); // version made by
                Write(GeneralPurpose, stream); // general purpose
                Write(StoreMethod, stream); // store method
                Write(DosDateTime, stream); // Dos date, time
                Write(Checksum, stream); // CRC-32
                Write((uint) CompressedLength, stream); // compressed size
                Write((uint) UncompressedLength, stream); // uncompressed size
                Write((ushort) Name.Length, stream); // file name length
                Write(0, stream); // extra field length
                Write(Encoding.ASCII.GetBytes(Name), stream);
                stream.Flush();
            }

            public void EmitFile(Stream stream)
            {
                using (var fileStream = File.OpenRead(FileName))
                {
                    switch (StoreMethod)
                    {
                        case 0:
                            StoreFile(stream, fileStream);
                            break;

                        case 8:
                            DeflateFile(stream, fileStream);
                            break;
                    }
                }

                Write(Checksum, stream);
                Write((uint) CompressedLength, stream);
                Write((uint) UncompressedLength, stream);
            }

            private void StoreFile(Stream archiveStream, Stream sourceStream)
            {
                var count = 1;
                var buffer = new byte[1024];
                var crc = Crc32.BeginChecksum();

                while (count != 0)
                {
                    count = sourceStream.Read(buffer, 0, buffer.Length);
                    UncompressedLength += count;
                    crc = Crc32.UpdateChecksum(crc, buffer, 0, count);
                    archiveStream.Write(buffer, 0, count);
                }

                Checksum = Crc32.EndChecksum(crc);
                CompressedLength = UncompressedLength;
            }

            private void DeflateFile(Stream archiveStream, Stream sourceStream)
            {
                using (var counterStream = new CounterStream(archiveStream, true))
                {
                    using (var deflateStream = new DeflateStream(counterStream, CompressionMode.Compress, true))
                    {
                        var count = 1;
                        var buffer = new byte[1024];
                        var crc = Crc32.BeginChecksum();

                        while (count != 0)
                        {
                            count = sourceStream.Read(buffer, 0, buffer.Length);
                            UncompressedLength += count;
                            crc = Crc32.UpdateChecksum(crc, buffer, 0, count);
                            deflateStream.Write(buffer, 0, count);
                        }

                        Checksum = Crc32.EndChecksum(crc);
                    }

                    CompressedLength = (int) counterStream.Position;
                }
            }

            public void EmitCatalogFileHeader(Stream stream)
            {
                Write(0x02014b50, stream); // central directory
                Write(0x14, stream); // version made by
                Write(0x14, stream); // version required
                Write(GeneralPurpose, stream); // general purpose
                Write(StoreMethod, stream); // store method
                Write(DosDateTime, stream); // Dos date, time
                Write(Checksum, stream); // CRC-32
                Write((uint) CompressedLength, stream); // compressed size
                Write((uint) UncompressedLength, stream); // uncompressed size
                Write((ushort) Name.Length, stream); // file name length
                Write(0, stream); // extra field length
                Write(0, stream); // file comment length
                Write(0, stream); // disk number start
                Write(0, stream); // internal file attributes
                Write((uint) 0x00000020, stream); // external file attributes
                Write((uint) RelativeOffset, stream); // relative offset of local header
                Write(Encoding.ASCII.GetBytes(Name), stream);
                stream.Flush();
            }
        }

        // -------------------------------------------------------------------------------------------------

        private static class Crc32
        {
            private static readonly uint[] table = new uint[]
            {
                0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA,
                0x076DC419, 0x706AF48F, 0xE963A535, 0x9E6495A3,
                0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
                0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91,
                0x1DB71064, 0x6AB020F2, 0xF3B97148, 0x84BE41DE,
                0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
                0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC,
                0x14015C4F, 0x63066CD9, 0xFA0F3D63, 0x8D080DF5,
                0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
                0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B,
                0x35B5A8FA, 0x42B2986C, 0xDBBBC9D6, 0xACBCF940,
                0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
                0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116,
                0x21B4F4B5, 0x56B3C423, 0xCFBA9599, 0xB8BDA50F,
                0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
                0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D,
                0x76DC4190, 0x01DB7106, 0x98D220BC, 0xEFD5102A,
                0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
                0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818,
                0x7F6A0DBB, 0x086D3D2D, 0x91646C97, 0xE6635C01,
                0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
                0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457,
                0x65B0D9C6, 0x12B7E950, 0x8BBEB8EA, 0xFCB9887C,
                0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
                0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2,
                0x4ADFA541, 0x3DD895D7, 0xA4D1C46D, 0xD3D6F4FB,
                0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
                0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9,
                0x5005713C, 0x270241AA, 0xBE0B1010, 0xC90C2086,
                0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
                0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4,
                0x59B33D17, 0x2EB40D81, 0xB7BD5C3B, 0xC0BA6CAD,
                0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
                0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683,
                0xE3630B12, 0x94643B84, 0x0D6D6A3E, 0x7A6A5AA8,
                0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
                0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE,
                0xF762575D, 0x806567CB, 0x196C3671, 0x6E6B06E7,
                0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
                0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5,
                0xD6D6A3E8, 0xA1D1937E, 0x38D8C2C4, 0x4FDFF252,
                0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
                0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60,
                0xDF60EFC3, 0xA867DF55, 0x316E8EEF, 0x4669BE79,
                0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
                0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F,
                0xC5BA3BBE, 0xB2BD0B28, 0x2BB45A92, 0x5CB36A04,
                0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
                0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A,
                0x9C0906A9, 0xEB0E363F, 0x72076785, 0x05005713,
                0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
                0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21,
                0x86D3D2D4, 0xF1D4E242, 0x68DDB3F8, 0x1FDA836E,
                0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
                0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C,
                0x8F659EFF, 0xF862AE69, 0x616BFFD3, 0x166CCF45,
                0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
                0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB,
                0xAED16A4A, 0xD9D65ADC, 0x40DF0B66, 0x37D83BF0,
                0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
                0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6,
                0xBAD03605, 0xCDD70693, 0x54DE5729, 0x23D967BF,
                0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
                0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D
            };

            public static uint BeginChecksum()
            {
                return 0xffffffff;
            }

            public static uint UpdateChecksum(uint crc, byte[] bytes, int offset, int count)
            {
                for (var i = offset; i < count; i++)
                {
                    var index = (byte) (((crc) & 0xff) ^ bytes[i]);
                    crc = ((crc >> 8) ^ table[index]);
                }

                return crc;
            }

            public static uint EndChecksum(uint crc)
            {
                return ~crc;
            }
        }

        // -------------------------------------------------------------------------------------------------

        private sealed class CounterStream : Stream
        {
            private int Count { get; set; }
            private Stream InternalStream { get; set; }
            private bool LeaveOpen { get; set; }

            public CounterStream(Stream stream, bool leaveOpen)
            {
                if (stream == null)
                {
                    throw new ArgumentNullException("stream");
                }

                InternalStream = stream;
                LeaveOpen = leaveOpen;
            }

            public override bool CanRead
            {
                get { return false; }
            }

            public override bool CanSeek
            {
                get { return false; }
            }

            public override bool CanWrite
            {
                get { return InternalStream.CanWrite; }
            }

            public override void Flush()
            {
                InternalStream.Flush();
            }

            public override long Length
            {
                get { throw new NotSupportedException(); }
            }

            public override long Position
            {
                get { return Count; }
                set { throw new NotSupportedException(); }
            }

            public override int Read(byte[] buffer, int offset, int count)
            {
                throw new NotSupportedException();
            }

            public override long Seek(long offset, SeekOrigin origin)
            {
                throw new NotSupportedException();
            }

            public override void SetLength(long value)
            {
                throw new NotSupportedException();
            }

            public override void Write(byte[] buffer, int offset, int count)
            {
                InternalStream.Write(buffer, offset, count);
                Count += count;
            }

            protected override void Dispose(bool disposing)
            {
                try
                {
                    if (disposing)
                    {
                        if (InternalStream != null && LeaveOpen == false)
                        {
                            InternalStream.Close();
                        }
                    }
                }

                finally
                {
                    InternalStream = null;
                    base.Dispose(disposing);
                }
            }
        }

        // -------------------------------------------------------------------------------------------------

        private static uint GetDosDateTime(DateTime date)
        {
            return (uint) (
                ((date.Year - 1980 & 0x7f) << 25) |
                    ((date.Month & 0xF) << 21) |
                        ((date.Day & 0x1F) << 16) |
                            ((date.Hour & 0x1F) << 11) |
                                ((date.Minute & 0x3F) << 5) |
                                    (date.Second >> 1));
        }

        private static void Write(uint number, Stream stream)
        {
            var buffer = BitConverter.GetBytes(number);
            stream.Write(buffer, 0, buffer.Length);
        }

        private static void Write(ushort value, Stream stream)
        {
            var buffer = BitConverter.GetBytes(value);
            stream.Write(buffer, 0, buffer.Length);
        }

        private static void Write(byte[] buffer, Stream stream)
        {
            stream.Write(buffer, 0, buffer.Length);
        }

        private static string NormalizeFileName(string fileName, bool flatten)
        {
            if (flatten)
            {
                return Path.GetFileName(fileName);
            }

            var name = fileName.Replace("\\", "/");
            name = name.Replace("../", "");
            var i = name.IndexOf(':');

            if (i != -1)
            {
                name = name.Substring(i + (Path.IsPathRooted(name) ? 2 : 1));
            }

            return name;
        }
    }
}